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Better management and economy of the N resource in Ireland.
Ryan, Michael
Ryan, Michael
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1998-09-01
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Ryan, M., Better management and economy of the N resource in Grassland:Relative denitrification rates in surface and subsurface mineral soil layers , End of Project Reports, Teagasc, 1998.
Abstract
The project, which was carried out at Johnstown Castle, was concerned
with measuring denitrification at depth in grazed grass plots
receiving 362 kg fertiliser N per ha. Reports in the scientific literature
had indicated that such was likely, given the conditions necessary for
the denitrifying microbial reactions to take place.
In one experiment, denitrification was detected in measurable amounts
to 90cm soil depth in spring-summer, using the acetylene block technique.
A second more extensive experiment carried out under similar
conditions within one year from March to August and from October to
March looked at denitrification in greater detail to 50 cm deep.
Results showed the importance of soil water and soil ammonium (NH4)
to rate of denitrification. The rate was much greater in the 0-10 cm
layer than in the lower layers in both time periods. Of the total denitrification
occurring in the 0-50 cm layers in the year, which was 16.6
kg N per ha, 80% occurred at 0-10 cm with 62% occurring in the second
time period, October to March.